First Greek Writer by Arthur Sidgwick is available for download on the Textkit Greek resources page. There is also an answer key for the exercises. I have decided to (finally) work my way through a Greek composition text. At the moment I am reading through Sidgwick's notes, and then I'll begin the actual exercises. The notes themselves are quite helpful - sometimes Sidgwick has a way of stating a rule which is much simpler and easier to remember than other presentations I have read. I'll post any thoughts on the book here, if they arise.